Professor Christian Jakob
- Date: Tuesday 12 October 2021, 14:00 – 15:00
- Location: Online
- Type: Institute for Climate and Atmospheric Science, Seminars, Earth and Environment
- Cost: Free
Prof Christian Jakob (Monash University) will be giving a talk on 'Convection and large-scale interactions - an observational perspective'
Abstract: The faithful representation of tropical convection in weather and climate models remains one of most difficult tasks in atmospheric science. This is so, because the complex interactions of small-, meso- and large-scale processes that occur in convection need to be parametrized in those models. Much of the recent work in understanding the behavior of convection and in improving parametrizations has utilized high-resolution cloud models, with often only tenuous connections back to observations. This talk aims to illustrate the vastly underestimated potential of modern observations to inform understanding and parametrization.
Since the 1990s, a research radar network around Darwin in tropical Australia has been instrumental in significantly improving our understanding of the scale interactions associated with tropical convection. Its use has culminated in a unique, 16-year long data set for atmospheric convection research. We use this data set to examine the key ingredients of tropical convective cloud ensembles, such as cloud number, size, depth and in-cloud vertical motion and their relationship to the large-scale state of the atmosphere.
We show that convective heating in an area is largely dominated by the fraction of the area that experiences convection. We show that the most intense convection is associated with large clouds that occur in a dry and often descending atmosphere, while the largest area-average rain results from a moderate number of moderate size clouds embedded in a humid and ascending atmosphere.
Combining cloud-structure information with radar-based estimates of in-cloud vertical velocity, enables us to estimate convective mass-fluxes over long periods of time and large areas. We use this information to estimate the vertical structure of entrainment and detrainment and its relationship to the convective environment.
Finally, we briefly investigate if and how some of the behaviour of convection found at the radar scale transfers to larger to near-global scales.
Bio: Christian is the Professor for Climate Modelling at Monash’s School of Earth, Atmosphere and Environment and a Chief Investigator in the ARC Centre of Excellence for Climate Extremes. He was awarded his PhD in Meteorology by the Ludwig Maximilians University, Munich, in 2001. As a research, then senior research, scientist for the European Centre for Medium-Range Weather Forecasts from 1993 to 2001, he worked on the development and evaluation of the model representation of clouds, convection and precipitation. From 2002 to 2007 he was senior and principal research scientist of the Australian Bureau of Meteorology, and joined Monash University in 2007.
Christian’s experience and current interests are in the development and evaluation of the processes crucial to the energy and water cycles in global atmospheric models. Internationally, he is engaged in many scientific and collaborative activities. He is the current Co-chair of the World Climate Research Programme’s (WCRP) Digital Earths Lighthouse Activity. Before that, he co-chaired the WCRP Modelling Advisory Council (2012-2017) and led the Working Group on Numerical Experimentation (2008-2012).
Christian was a Lead Author for the Intergovernmental Panel on Climate Change 5th Assessment Report, Working Group 1. In 2016 he won the Ascent Award of the American Geophysical Union’s Atmospheric Sciences Section, and in 2018 he was elected a Fellow of the Australian Meteorological and Oceanographic Society (AMOS). He was awarded the AMOS Morton Medal in 2019.